Systems and methods for producing a sugar stream

ABSTRACT

An improved dry grind system and method for producing a sugar stream from grains or similar carbohydrate sources and/or residues, such as for biofuel production. In particular, a sugar/carbohydrate stream, which includes a desired Dextrose Equivalent (DE) where DE describes the degree of conversion of starch to dextrose (aka glucose) and/or has had removed therefrom an undesirable amount of unfermentable components, can be produced after saccharification and prior to fermentation (or other sugar conversion process), with such sugar stream being available for biofuel production, e.g., alcohol production, or other processes. In addition, the systems and methods also can involve the removal of certain grain components, e.g., corn kernel components, including protein, oil and/or fiber, prior to fermentation or other conversion systems. In other words, sugar stream production and/or grain component separation occurs on the front end of the system and method.

TECHNICAL FIELD

The present invention relates generally to systems and methods for usein the biofuel, biochemical, food, feed, nutrition, and/or pharmacyindustries and, more specifically, to improved dry grind systems andmethods for producing a sugar stream, such as for biofuel production.

BACKGROUND

The conventional processes for producing various types of biofuels, suchas alcohol and other chemicals, from grains generally follow similarprocedures. Wet mill processing plants convert, for example, corn grain,into several different co-products, such as germ (for oil extraction),gluten feed (high fiber animal feed), gluten meal (high protein animalfeed) and starch-based products such as alcohol (e.g., ethanol orbutanol), high fructose corn syrup, or food and industrial starch. Drygrind plants generally convert grains, such as corn, into two products,namely alcohol (e.g., ethanol or butanol) and distiller's grains withsolubles. If sold as wet animal feed, distiller's wet grains withsolubles are referred to as DWGS. If dried for animal feed, distiller'sdried grains with solubles are referred to as DDGS. This co-productprovides a secondary revenue stream that offsets a portion of theoverall alcohol production cost.

With respect to the wet mill process, FIG. 1 is a flow diagram of atypical wet mill alcohol (e.g., ethanol) production process 10. Theprocess 10 begins with a steeping step 12 in which grain (e.g., corn) issoaked for 24 to 48 hours in a solution of water and sulfur dioxide inorder to soften the kernels for grinding, leach soluble components intothe steep water and loosen the protein matrix with the endosperm. Cornkernels contain mainly starch, fiber, protein and oil. The mixture ofsteeped corn and water is then fed to a degermination mill step (firstgrinding) 14 in which the corn is ground in a manner that tears open thekernels and releases the germ so as to make a heavy density (8.5 to 9.5Be) slurry of the ground components, primarily a starch slurry. This isfollowed by a germ separation step 16 that occurs by flotation and useof a hydrocyclone(s) to separate the germ from the rest of the slurry.The germ is the part of the kernel that contains the oil found in corn.The separated germ stream, which contains some portion of the starch,protein and fiber, goes to germ washing to remove starch and protein,and then to a dryer to produce about 2.7 to 3.2 Lb. (dry basis) of germper bushel of corn. The dry germ has about 50% oil content on a drybasis.

The remaining slurry, which is now devoid of germ, but containing fiber,gluten (i.e., protein) and starch, is then subjected to a fine grindingstep (second grinding) 20 in which there is total disruption ofendosperm and release of endosperm components, namely gluten and starch,from the fiber. This is followed by a fiber separation step 22 in whichthe slurry is passed through a series of screens in order to separatethe fiber from starch and gluten and to wash the fiber clean of glutenand starch. The fiber separation stage 22 typically employs staticpressure screens or rotating paddles mounted in a cylindrical screen(Paddle Screens). Even after washing, the fiber from a typical wet grindmill contains 15 to 20% starch. This starch is sold with the fiber asanimal feed. The remaining slurry, which is now generally devoid offiber, is subjected to a gluten separation step 24 in whichcentrifugation or hydrocyclones separate starch from the gluten. Thegluten stream goes to a vacuum filter and dryer to produce gluten(protein) meal.

The resulting purified starch co-product then can undergo a jet cookingstep 26 to start the process of converting the starch to sugar. Jetcooking refers to a cooking process performed at elevated temperaturesand pressures, although the specific temperatures and pressures can varywidely. Typically, jet cooking occurs at a temperature of about 93 to110° C. (about 200 to 230° F.) and a pressure of about 30 to 50 psi.This is followed by liquefaction 28, saccharification 30, fermentation32, yeast recycling 34, and distillation/dehydration 36 for a typicalwet mill biofuels system. Liquefaction occurs as the mixture or “mash”is held at 90 to 95° C. in order for alpha-amylase to hydrolyze thegelatinized starch into maltodextrins and oligosaccharides (chains ofglucose sugar molecules) to produce a liquefied mash or slurry. In thesaccharification step 30, the liquefied mash is cooled to about 50° C.and a commercial enzyme known as gluco-amylase is added. Thegluco-amylase hydrolyzes the maltodextrins and short-chainedoligosaccharides into single glucose sugar molecules to produce aliquefied mash. In the fermentation step 32, a common strain of yeast(Saccharomyces cerevisae) is added to metabolize the glucose sugars intoethanol and CO₂.

Upon completion, the fermentation mash (“beer”) will contain about 15%to 18% ethanol (volume/volume basis), plus soluble and insoluble solidsfrom all the remaining grain components. The solids and some liquidremaining after fermentation go to an evaporation stage where yeast canbe recovered as a byproduct. Yeast can optionally be recycled in a yeastrecycling step 34. In some instances, the CO₂ is recovered and sold as acommodity product. Subsequent to the fermentation step 32 is thedistillation and dehydration step 36 in which the beer is pumped intodistillation columns where it is boiled to vaporize the ethanol. Theethanol vapor is separated from the water/slurry solution in thedistillation columns and alcohol vapor (in this instance, ethanol) exitsthe top of the distillation columns at about 95% purity (190 proof). The190 proof ethanol then goes through a molecular sieve dehydrationcolumn, which removes the remaining residual water from the ethanol, toyield a final product of essentially 100% ethanol (199.5 proof). Thisanhydrous ethanol is now ready to be used for motor fuel purposes.Further processing within the distillation system can yield food gradeor industrial grade alcohol.

No centrifugation step is necessary at the end of the wet mill ethanolproduction process 10 as the germ, fiber and gluten have already beenremoved in the previous separation steps 16, 22, 24. The “stillage”produced after distillation and dehydration 36 in the wet mill process10 is often referred to as “whole stillage” although it also istechnically not the same type of whole stillage produced with atraditional dry grind process described in FIG. 2 below, since noinsoluble solids are present. Other wet mill producers may refer to thistype of stillage as “thin” stillage.

The wet grind process 10 can produce a high quality starch product forconversion to alcohol, as well as separate streams of germ, fiber andprotein, which can be sold as co-products to generate additional revenuestreams. However, the overall yields for various co-products can be lessthan desirable and the wet grind process is complicated and costly,requiring high capital investment as well as high-energy costs foroperation.

Because the capital cost of wet grind mills can be so prohibitive, somealcohol plants prefer to use a simpler dry grind process. FIG. 2 is aflow diagram of a typical dry grind alcohol (e.g., ethanol) productionprocess 100. As a general reference point, the dry grind method 100 canbe divided into a front end and a back end. The part of the method 100that occurs prior to distillation 110 is considered the “front end,” andthe part of the method 100 that occurs after distillation 110 isconsidered the “back end.” To that end, the front end of the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels can be passed through hammer mills for grinding into meal or afine powder. The screen openings in the hammer mills or similar devicestypically are of a size 6/64 to 9/64 inch, or about 2.38 mm to 3.57 mm,but some plants can operate at less than or greater than these screensizes. The resulting particle distribution yields a very wide spread,bell type curve, which includes particle sizes as small as 45 micron andas large as 2 to 3 mm. The majority of the particles are in the range of500 to 1200 micron, which is the “peak” of the bell curve.

After the grinding step 102, the ground meal is mixed with cook water tocreate a slurry at slurry step 103 and a commercial enzyme calledalpha-amylase is typically added (not shown). The slurry step 103 isfollowed by a liquefaction step 104 whereat the pH is adjusted to about5.2 to 5.8 and the temperature maintained between about 50° C. to 105°C. so as to convert the insoluble starch in the slurry to solublestarch. Various typical liquefaction processes, which occur at thisliquefaction step 104, are discussed in more detail further below. Thestream after the liquefaction step 104 has about 30% dry solids (DS)content, but can range from about 29-36%, with all the componentscontained in the corn kernels, including starch/sugars, protein, fiber,starch, germ, grit and oil and salts, for example. Higher solids areachievable, but this requires extensive alpha amylase enzyme to rapidlybreakdown the viscosity in the initial liquefaction step. Theregenerally are several types of solids in the liquefaction stream: fiber,germ and grit.

Liquefaction may be followed by separate saccharification andfermentation steps, 106 and 108, respectively, although in mostcommercial dry grind ethanol processes, saccharification andfermentation can occur simultaneously. This single step is referred toin the industry as “Simultaneous Saccharification and Fermentation”(SSF). Both saccharification and SSF can take as long as about 50 to 60hours. Fermentation converts the sugar to alcohol. Yeast can optionallybe recycled in a yeast recycling step (not shown) either during thefermentation process or at the very end of the fermentation process.Subsequent to the fermentation step 108 is the distillation (anddehydration) step 110, which utilizes a still to recover the alcohol.

Finally, a centrifugation step 112 involves centrifuging the residualsproduced with the distillation and dehydration step 110, i.e., “wholestillage” in order to separate the insoluble solids (“wet cake”) fromthe liquid (“thin stillage”). The liquid from the centrifuge containsabout 5% to 12% DS. The “wet cake” includes fiber, of which theregenerally are three types: (1) pericarp, with average particle sizestypically about 1 mm to 3 mm; (2) tricap, with average particle sizesabout 500 micron; (3) and fine fiber, with average particle sizes ofabout 250 micron. There may also be proteins with a particle size ofabout 45 to 300 micron.

The thin stillage typically enters evaporators in an evaporation step114 in order to boil or flash away moisture, leaving a thick syrup whichcontains the soluble (dissolved) solids (mainly protein andstarches/sugars) from the fermentation (25 to 40% dry solids) along withresidual oil and fine fiber. The concentrated slurry can be sent to acentrifuge to separate the oil from the syrup in an oil recovery step116. The oil can be sold as a separate high value product. The oil yieldis normally about 0.6 lb./bu of corn with high free fatty acids content.This oil yield recovers only about ⅓ of the oil in the corn, with partof the oil passing with the syrup stream and the remainder being lostwith the fiber/wet cake stream. About one-half of the oil inside thecorn kernel remains inside the germ after the distillation step 110,which cannot be separated in the typical dry grind process usingcentrifuges. The free fatty acids content, which is created when the oilis heated and exposed to oxygen throughout the front and back-endprocess, reduces the value of the oil. The (de-oil) centrifuge onlyremoves less than 50% because the protein and oil make an emulsion,which cannot be satisfactorily separated.

The syrup, which has more than 10% oil, can be mixed with thecentrifuged wet cake, and the mixture may be sold to beef and dairyfeedlots as Distillers Wet Grain with Solubles (DWGS). Alternatively,the wet cake and concentrated syrup mixture may be dried in a dryingstep 118 and sold as Distillers Dried Grain with Solubles (DDGS) todairy and beef feedlots. This DDGS has all the corn and yeast proteinand about 75% of the oil in the starting corn material. But the value ofDDGS is low due to the high percentage of fiber, and in some cases theoil is a hindrance to animal digestion and lactating cow milk quality.

Further with respect to the liquefaction step 104, FIG. 3 is a flowdiagram of various typical liquefaction processes that define theliquefaction step 104 in the dry grind process 100. Again, the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels are passed through hammer mills or similar milling systems suchas roller mills, flaking mills, impacted mill or pin mills for grindinginto meal or a fine powder. The grinding step 102 is followed by theliquefaction step 104, which itself includes multiple steps as isdiscussed next.

Each of the various liquefaction processes generally begins with theground grain or similar material being mixed with cook and/or backsetwater, which can be sent from evaporation step 114 (FIG. 2), to create aslurry at slurry tank 130 whereat a commercial enzyme calledalpha-amylase is typically added (not shown). The pH is adjusted here,as is known in the art, to about 5.2 to 5.8 and the temperaturemaintained between about 50° C. to 105° C. so as to allow for the enzymeactivity to begin converting the insoluble starch in the slurry tosoluble liquid starch. Other pH ranges, such as from pH 4.0-7.0, may beutilized and an acid treatment system using sulfuric acid, for example,can be used as well for pH control and conversion of the starches tosugars.

After the slurry tank 130, there are normally three optional pre-holdingtank steps, identified in FIG. 3 as systems A, B, and C, which may beselected depending generally upon the desired temperature and holdingtime of the slurry. With system A, the slurry from the slurry tank 130is subjected to a jet cooking step 132 whereat the slurry is fed to ajet cooker, heated to about 120° C., held in a U-tube or similar holdingvessel for about 2 to about 30 minutes, then forwarded to a flash tank.In the flash tank, the injected steam flashes out of the liquid stream,creating another particle size reduction and providing a means forrecovering the injected stream. The jet cooker creates a sheering forcethat ruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and allows for rapid hydration of the starchgranules. It is noted here that system A may be replaced with a wetgrind system. With system B, the slurry is subjected to a secondaryslurry tank step 134 whereat the slurry is maintained at a temperaturefrom about 90° C. to 100° C. for about 10 min to about one hour. Withsystem C, the slurry from the slurry tank 130 is subjected to asecondary slurry tank—no steam step 136, whereat the slurry from theslurry tank 130 is sent to a secondary slurry tank, without any steaminjection, and maintained at a temperature of about 80° C. to 90° C. forabout 1 to 2 hours. Thereafter, the slurry from each of systems A, B,and C is forwarded, in series, to first and second holding tanks 140 and142 for a total holding time of about 60 minutes to about 4 hours attemperatures of about 80° C. to 90° C. to complete the liquefaction step104, which then is followed by the saccharification and fermentationsteps 106 and 108, along with the remainder of the process 100 of FIG.2. While two holding tanks are shown here, it should be understood thatone holding tank, more than two holding tanks, or no holding tanks maybe utilized.

In today's typical grain to biofuel plants (e.g., corn to alcoholplants), many systems, particularly dry grind systems, process theentire corn kernel through fermentation and distillation. Such designsrequire about 30% more front-end system capacity because there is onlyabout 70% starch in corn, with less for other grains and/or biomassmaterials. Additionally, extensive capital and operational costs arenecessary to process the remaining non-fermentable components within theprocess. By removing undesirable, unfermentable components prior tofermentation (or other reaction process), more biofuel, biochemical andother processes become economically desirable.

It thus would be beneficial to provide an improved dry milling methodand system that produces a cleaner sugar stream, such as for biofuelproduction, that may be similar to the sugar stream produced byconventional wet corn milling systems, but at a fraction of the cost andgenerate additional revenue from oil, protein and/or fiber yields, forexample.

SUMMARY OF THE INVENTION

The present invention provides for a dry milling method and system thatproduces a cleaner sugar stream, such as for biofuel production, thatmay be similar to the sugar stream produced by conventional wet cornmilling systems, but at a fraction of the cost, and generate additionalrevenue from oil, protein and/or fiber yields, for example.

In one embodiment of the invention, a method for producing a sugarstream is provided and includes mixing a ground grain and/or graincomponent with a liquid to produce a slurry including starch andunfermentable components. The method further includes subjecting theslurry to liquefaction followed by saccharification to convert thestarch to simple sugars and produce a stream including the simple sugarsand unfermentable components. After saccharification, but prior tofurther processing of the simple sugars, the method further includesseparating the stream into a solids portion including unfermentablecomponents and a liquid portion including the simple sugars, wherein theliquid portion defines a sugar stream having a dextrose equivalent of atleast 20 D.E. and a total unfermentable solids fraction that is lessthan or equal to 30% of the total solids content.

In another embodiment of the invention, a method for producing a sugarstream is provided and includes mixing a ground grain and/or graincomponent with a liquid to produce a slurry including starch andunfermentable components. The method further includes subjecting theslurry to liquefaction followed by saccharification to convert thestarch to simple sugars and produce a stream including the simple sugarsand unfermentable components. After saccharification, but prior to asugar conversion process, the method includes separating the stream intoa solids portion, including unfermentable components and a liquidportion, including the simple sugars, wherein the liquid portion definesa sugar stream having a dextrose equivalent of at least 80 D.E. and atotal unfermentable solids fraction that is less than or equal to 10% ofthe total solids content. The method further includes subjecting thesugar stream to the sugar conversion process.

In yet another embodiment of the invention, a system for producing asugar stream is provided that includes a slurry tank in which groundgrain and/or grain component mixes with a liquid to produce a slurry,including starch and unfermentable components, and a liquefaction and asaccharification system that receives the slurry and whereat the starchis converted to simple sugars thereby producing a stream including thesimple sugars and unfermentable components. The system further includesa first separation device, which receives and separates the stream intoa solids portion, including unfermentable components and a liquidportion, including the simple sugars, wherein the liquid portion definesa sugar stream having a dextrose equivalent of at least 20 D.E. and atotal unfermentable solids fraction that is less than or equal to 30% ofthe total solids content and a biofuel and/or biochemical device thatreceives the sugar stream to produce biofuel and/or biochemicals fromthe simple sugars.

The features and objectives of the present invention will become morereadily apparent from the following Detailed Description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,with a detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a flow diagram of a typical wet mill alcohol productionprocess;

FIG. 2 is a flow diagram of a typical dry grind alcohol productionprocess;

FIG. 3 is a flow diagram of various typical liquefaction processes in atypical dry grind alcohol production process;

FIG. 4 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with an embodiment of theinvention;

FIG. 5 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with another embodiment of theinvention; and

FIG. 6 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with yet another embodiment ofthe invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIGS. 1 and 2 have been discussed above and represent flow diagrams of atypical wet mill and dry grind alcohol production process, respectively.FIG. 3, likewise, has been discussed above and represents varioustypical liquefaction processes in a typical dry grind alcohol productionprocess.

FIGS. 4-6 illustrate embodiments of a dry grind system and method 200,300, 300 a for producing a sugar stream from grains or similarcarbohydrate sources and/or residues, such as for biofuel production, inaccordance with the present invention. As further discussed in detailbelow, a sugar/carbohydrate stream, which includes a desired DextroseEquivalent (DE) where DE describes the degree of conversion of starch todextrose (aka glucose) and/or has had removed therefrom an undesirableamount of unfermentable components, can be produced aftersaccharification and prior to fermentation (or other sugar conversionprocess), with such sugar stream being available for biofuel production,e.g., alcohol production, or other processes. In addition, the presentsystems and methods 200, 300, 300 a also can involve the removal ofcertain grain components, e.g., corn kernel components, includingprotein, oil and/or fiber, prior to fermentation or other conversionsystems, as further discussed below. In other words, sugar streamproduction and/or grain component separation occurs on the front end ofthe system and method 200, 300, 300 a.

For purposes herein, in one example, the resulting sugar stream that maybe desirable after saccharification, but before fermentation, such asfor use in biofuel production, can be a stream where the starch/sugarsin that stream define at least a 90 DE and/or where the total insoluble(unfermentable) solids fraction of the stream is less than or equal to5% of the total solids content in the stream. In other words, at least90% of the total starch/sugar in that stream is dextrose and/or nogreater than 5% of the total solids in that stream includesnon-fermentable components. In another example, the sugar stream maydefine at least 95 DE. In another example, the resulting sugar streammay define at least 98 DE. In yet another example, the starch/sugars inthe stream can define at least a 20, 30, 40, 50, 60, 70, or 80 DE. Inanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 3% of the total solids content inthe stream. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 1%. In stillanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 10%, 15%, 20%, 25%, or 30%. In otherwords, the total fermentable content (fermentable solids fraction) ofthe stream may be no more than 30, 40, 50, 60, 70, 75, 80, 85, 90, 95,97, or 99% of the total solids content in the stream. In anotherexample, on a dry mass basis, the weight % fermentable material in thesugar stream that may be desired is greater than or equal to 80%. Inanother example, on a dry mass basis, the weight % fermentable materialin a sugar stream is greater than or equal to 85%, 90%, 95%, 98%, or99%.

In addition, although the system and method 200, 300, 300 a describedherein will generally focus on corn or kernel components, virtually anytype of grain, whether whole and fractionated or any carbohydratesource, including, but not limited to, wheat, barley, sorghum, rye,rice, oats, sugar cane, tapioca, cassava or the like, as well as otherbiomass products, can be used. And broadly speaking, it should beunderstood that the entire grain or biomass or less than the entiregrain, e.g., corn and/or grit and/or endosperm or biomass, may be groundand/or used in the system and method 200, 300, 300 a.

With further reference now to FIG. 4, in this dry grind system andmethod 200, grains such as corn, for example, can be subjected to afirst grinding step 202, which involves use of a hammer mill, rollermill, pin mill, impact mill, flaking mill or the like, to grind corn toparticle sizes less than about 7/64 inch or, in another example, lessthan about 10/64 inch and allow for the release of oil therefrom. In oneexample, the screen size for separating the particles can range fromabout 24/64 inch to about 2/64 inch. In another example, the resultingparticle sizes are from about 50 micron to 3 mm. The grinding also helpsbreak up the bonds between the fiber, protein, starch and germ. In oneexample, screen size or resulting particle size may have little to noimpact on the ability to separate the sugar from the remaining kernel orsimilar raw material component(s).

Next, the ground corn flour is mixed with backset liquid at slurry tank204 to create a slurry. Optionally, fresh water may be added so as tolimit the amount of backset needed here. The backset liquid includesoverflow from a second separation step 230, which is a later step in themethod 200 and is discussed further below. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 204 or in a slurryblender (not shown) between steps 202 and 204. The slurry may be heatedat the slurry tank 204 from about 66° C. (150° F.) to about 93° C. (200°F.) for about 10 minutes to about 120 minutes. The stream from theslurry tank 204 contains about 0.5 lb/bu free oil and about 1.5 lb/bugerm (particle size ranges from about 50 micron to about 3 mm), 1.8lb/bu grit (particle size ranges from about 50 micron to about 3 mm),which can include starch and 4.2 lb/bu fiber (particle size ranges fromabout 50 micron to about 3 mm).

The stream from the slurry tank 204 next may be subjected to an optionalsecond grinding/particle size reduction step 206, which may involve useof a disc mill or the like, to further grind the corn to particle sizesless than about 850 micron and allow for additional release of oil andprotein/starch complexes therefrom. In another example, the particlesizes are from about 300 micron to 650 mm. The grinding further helpscontinue to break up the bonds between the fiber, protein and starch andfacilitates the release of free oil from germ particles. Prior tosubjecting the stream from the slurry tank to the secondgrinding/particle size reduction step 206, the slurry may be subjectedto an optional dewatering step, which uses dewatering equipment, e.g., apaddle screen, a vibration screen, screen decanter centrifuge or conicscreen centrifuge, a pressure screen, a preconcentrator, a filter pressor the like, to remove a desired amount of liquids therefrom.

The further ground corn flour slurry or the stream from the slurry tank204, if the second grinding step 206 is not provided, next is subjectedto a liquefaction step 208, which itself can include multiple steps asdiscussed above and shown in FIG. 3. In one embodiment, the pH can beadjusted here to about 5.2 to 5.8 and the temperature maintained betweenabout 50° C. to 105° C. so as to convert the insoluble starch in theslurry to soluble or liquid starch. Other pH ranges, such as from pH4.0-7.0, may be utilized and an acid treatment system using sulfuricacid, for example, may be used as well for pH control and for conversionof the starches to sugars. The slurry may be further subjected to jetcooking whereat the slurry is fed to a jet cooker, heated to about 120°C., held for about 2 to 30 min., then forwarded to a flash tank. The jetcooker creates a sheering force that ruptures the starch granules to aidthe enzyme in reacting with the starch inside the granule and forhydrating the starch molecules. In another embodiment, the slurry can besubjected to a secondary slurry tank whereat steam is injected directlyto the secondary slurry tank and the slurry is maintained at atemperature from about 80° C. to 100° C. for about 30 min to one hour.In yet another embodiment, the slurry can be subjected to a secondaryslurry tank with no steam. In particular, the slurry is sent to asecondary slurry tank without any steam injection and maintained at atemperature of about 80° C. to 90° C. for 1 to 2 hours. Thereafter, theliquefied slurry may be forwarded to a holding tank for a total holdingtime of about 1 to 4 hours at temperatures of about 80° C. to 90° C. tocomplete the liquefaction step 208. With respect to the liquefactionstep 208, pH, temperature, and/or holding time may be adjusted asdesired.

The slurry stream after the liquefaction step 208 has about 28%-36% drysolids (DS) content with all the components contained in the cornkernels, including starches/sugars, protein, fiber, germ, grit, oil andsalts, for example. There generally are three types of solids in theliquefaction stream: fiber, germ and grit, which can include starch andprotein, with all three solids having about the same particle sizedistribution. The stream from the liquefaction step 208 contains about0.4 to about 0.6 lb/Bu free oil and about 1.5 lb/Bu germ particle (sizeranges from less about 50 micron to about 1 mm), 4.5 lb/Bu protein (sizeranges from about 50 micron to about 1 mm), and 4.25 lb/Bu fiber(particle size ranges from about 50 micron to about 3 mm). This streamnext is sent to an optional saccharification step 210 whereat complexcarbohydrate and oligosaccharides are further broken down into simplesugars, particularly single glucose sugar molecules (i.e., dextrose) toproduce a liquefied mash.

In particular, at the saccharification step 210, the slurry stream maybe subjected to a two-step cook process. The first part of the process,in one example, includes adjusting the pH to about 3.5 to 7.0, with thetemperature being maintained between about 30° C. to 100° C. for 1 to 6hours to further convert the insoluble starch in the slurry to solublestarch, particularly dextrose. In another example, the pH can be 5.2 to5.8 or 5.5, for example. In another example, the temperature can bemaintained at 80° C. for about 5 hours. Also, an enzyme, such asalpha-amylase may be added here. In one example, the amount ofalpha-amylase may be from about 0.01 to about 0.04 wt % of the slurrystream. In another example, the amount of alpha-amylase may be fromabout 0.04 to about 0.1 wt % of the total stream.

The second part of the process, in one example, may include adjustingthe pH to about 4.0 to 5.0, with the temperature being maintainedbetween about 30° C. to 175° C. for about 2 to 5 hours so as to furtherconvert the insoluble starch in the slurry to soluble starch,particularly dextrose. In another example, the pH can be 4.5. In anotherexample, the temperature can be maintained from about 54° C. (130° F.)to 74° C. (165° F.) for about 4 hours or up to about 60 hours. Anenzyme, such as glucoamylase, also may be added here. In one example,the amount of glucoamylase may be from about 0.01 to about 0.2 wt % ofthe slurry stream. In another example, the amount of glucoamylase may befrom about 0.08 to about 0.14 wt % of the slurry stream. Other enzymesor similar catalytic conversion agents may be added at this step orprevious steps that can enhance starch conversion to sugar or yieldother benefits, such as fiber or cellulosic sugar release, conversion ofproteins to soluble proteins, or the release of oil from the germ.

A liquefied sugar stream having a density of about 1.05 to 1.15 grams/cccan result here. At this point, the liquefied sugar stream, whether ornot optionally subjected to the saccharification step 201, may be noless than about 90 DE. In another example, the liquefied sugar streammay be no less than 20, 30, 40, 50, 60, 70, or 80 DE. In this example,the liquefied sugar stream may not be considered desirable or “clean”enough, such as for use in biofuel or biochemical production, becausethe total fermentable content of the stream may be no more than 75% ofthe total solids content in the stream. In this example, the liquefiedsugar stream can have a total solids fraction of about 28-36%, suchsolids including sugar, starch, fiber, protein, germ, oil and ash, forexample. In yet another example, the total fermentable content of thestream is no more than 30, 40, 50, 60, or 70% of the total solidscontent in the stream. The remaining solids are fiber, protein, oil, andash, for example.

After the optional saccharification step 210 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the liquefied sugar stream is subjected to afirst separation step 212. If the optional saccharification step 210 isnot provided here, the slurry stream from the liquefaction step 208 issent to first separation step 212. The first separation step 212 filtersa generally liquefied solution (about 60-80% by volume), which includessugar, free oil, protein, fine solids, fiber, grit and germ, and whichhas a total solids fraction of about 28%, with a range of 20% to 40%,but higher or low solids fractions can be produced, but may not beeconomical here. In particular, the first separation step 212 usesdewatering equipment, e.g., a paddle screen, a vibration screen, screendecanter centrifuge or conic screen centrifuge, a pressure screen, apreconcentrator, a filter press or the like, to accomplish substantialseparation of the solids portion, primarily fiber, germ, grit, which caninclude protein, from the liquid sugar portion, which primarily includessugar (e.g., dextrose), oil and fine solids. The solids portion, whichhas a total solids fraction of about 39%, may be sent on to a firstholding tank 214 and the liquid portion may be sent on and subjected toan optional oil separation step 216 to produce a cleaner, more desirablesugar stream, as further discussed below.

In one example, the dewatering equipment at the first separation step212 is a paddle screen, which includes a stationary cylinder screen withhigh speed paddles with rakes. The number of paddles on the paddlescreen can be in the range of 1 paddle per 4 to 8 inches or more ofscreen diameter. The number of paddles on the paddle screen can bemodified depending on the amount of solids in the feed. The gap betweenthe paddle screen and paddle can range from about 0.04 to 0.2 inch. Asmaller gap gives a drier cake with higher capacity and purer fiber, butloses more fine fiber to the filtrate stream. A larger gap gives awetter cake with lower capacity and purer liquid (less insoluble solid).The paddle speed can range from about 100 to 1,200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity, but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 25 micron to 450micron. In another example, the size of the screen openings can rangefrom about 25 micron to 300 micron. In another example, the screenopenings can range from 40 to 85 micron. In yet another example, thescreen openings are about 45 microns.

The now separated liquid portion or sugar stream from the firstseparation step 212 next can be subjected to an optional oil separationstep 216, which can use any type of oil separator, such as a mudcentrifuge, two or three phase decanter, disc decanter, two or threephase disc centrifuge, flotation tank, dissolved air floatationtank/system and the like, to separate oil from the sugar stream bytaking advantage of density differences. In particular, the sugar streamis used as heavy media liquid to float oil/emulsion/fine germ particle.In this example, the oil separation step 216 can remove a small amountof solids so as to reduce the total solids fraction to about 27%. Othersolid fraction ranges higher or lower can be achieved depending upon thestarting solids feeding the oil separation step 216.

There can be two or three or more phases discharged from the oilseparation step 216. As shown in FIG. 4, there are three phases with thefirst being a light phase, which primarily includes oil or anoil/emulsion layer. The second is an intermediate phase, which primarilyincludes sugars. The third phase is the solid phase, which primarilyincludes fine fiber, grit particle and protein. The underflowintermediate phase and solid phase can be combined as illustrated inFIG. 4 to produce a sugar stream, which may be forwarded to an underflowholding tank 218. If the optional oil separation step 216 is notpresent, the separated liquid portion or sugar stream from the firstseparation step 212 can be sent directly to holding tank 218.Alternatively, the separated liquid portion or sugar stream from thefirst separation step 212 can be sent on to fermentation step 226 toconvert, e.g., via a fermentor, the sugar to alcohol, such as ethanol orbutanol, or any other fermentation conversion process or similar sugarutilization process, as desired. If not initially provided afterliquefaction step 208 as shown in FIG. 4, the saccharification step 210may be provided just prior to fermentation step 226 or combinedtherewith so as to provide a single simultaneous saccharification andfermentation (SSF) step (not shown) to saccharify the sugar stream in amanner as discussed above.

The oil/emulsion layer can be forwarded to an optional oil polish step220 whereat the layer can be subjected to centrifugation, including athree phase decanter, multi phase disc centrifuge or the like toseparate pure oil from the emulsion and any fine germ particle. From theoptional oil polish step 220, the emulsion and fine germ particle can bedischarged as a heavy phase and returned to join up with the sugarstream from the oil separation step 216 at underflow holding tank 218.As another option, the emulsion and fine germ particle can be dischargedas a heavy phase and returned to the oil separation step 216. As anadditional option, the emulsion and fine germ particle can be joined upwith either the liquefied sugar stream from the saccharification step210 prior to the first separation step 212 or the solids portion fromthe first separation step 212. At the oil polish step 220, alcohol, suchas 200 proof alcohol from a distillation tower from a later distillationstep (not shown), as known in the art, can be added to the emulsion andfine germ particles so as to break the emulsion and extract oil from thefine germ particle, which normally are less than 100 micron.

The oil that is recovered at step 220 has a much more desirable qualityin terms of color and free fatty acid content (less than 7% and, inanother example, less than 5%) as compared to oil that is recovereddownstream, particularly oil recovered after fermentation, such as onthe back end. In particular, the color of pre-fermentation recovered oilis lighter in color and lower in free fatty acid content. The oil yieldat step 220 can reach about 0.9 lb/bu. The recovered oil here can beabout 95.5% oil and, in another example, the oil can be 99% oil.

Returning now to the sugar stream at holding tank 218, this stream issent on to a sugar separation step 222, which can include a clarifier,filtration centrifuge or the like, to separate heavier components,including residual protein, from the sugar stream. At this point, theseparated sugar stream may be no less than about 90 DE. In anotherexample, the liquefied sugar stream may be no less than 20, 30, 40, 50,60, 70, or 80 DE. In this example, the sugar stream here may beconsidered desirable or “clean” enough, such as for use in biofuelproduction, because the total insoluble (unfermentable) solids fractionof the stream is less than or equal to 5% of the total solids of thestream. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 3%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 1%. In still another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to10%, 15%, 20%, 25%, or 30%. In this example, the stream sent to sugarseparation step 222 may have a total solids fraction of 27%, such solidsincluding sugar, starch, fiber, protein and/or germ, for example.

After the sugar separation step 222, the sugar stream may then befurther subjected to an optional microfiltration (or similar filtration)step 224, which can include a micro-filter, membrane filtration,precoat/diatomaceous earth filter or the like, to produce a moredesirable sugar stream, which may be considered a purified or refinedsugar stream, by further separating out any remaining insolublecomponents, color, ash, minerals or the like. In one example, the filterscreen size here may be from about 5 to 100 microns. In another example,the filter screen size may be from about 8 to 50 microns. Due to theinput of water, the sugar stream can have a total solids fraction of20-27%. In this example, the sugar stream here may be consideredpurified or refined enough because the total insoluble (unfermentable)solids fraction of the stream is less than 5%. In another example, thetotal insoluble (unfermentable) solids fraction of the stream is lessthan or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%.

The microfiltration step 224 may be replaced by, or additionallyinclude, ultrafiltration, carbon column color removal, filter press,flotation and/or demineralization technologies (e.g., ion exchange).Resin refining, which includes a combination of carbon filtration anddemineralization in one step, can also be utilized for refining thesugars. Additionally, due to a low solids content of the sugar streamhere, an optional evaporation step (not shown) may be added hereafter tofurther concentrate the total solids fraction. The heavy components fromthe sugar separation step 222 and microfiltration step 224 can becombined together and sent back to meet up with the solids portion atthe first holding tank 214 or optionally may be recycled back to meet upwith the separated liquid portion or sugar stream from the firstseparation step 212, such as prior to the optional oil separation step216, to be again sent through the sugar separation step 222 and optionalmicrofiltration step 224. These heavier components or underflow, can bemore concentrated in total solids, at 28%.

The sugar stream from the microfiltration step 224 can be sent on tofermentation step 226 to convert, e.g., via a fermentor, the sugars toalcohol, such as ethanol or butanol or any other fermentation conversionprocess or similar sugar utilization process, followed by distillationand/or separation of the desired component(s) (not shown), which canrecover the alcohol or byproduct(s)/compound(s) produced, as is known inthe art. If not initially provided after liquefaction step 208 earlierin the system and method 200, as is shown in FIG. 4, the optionalsaccharification step 210 may be provided just prior to fermentationstep 226, here or combined therewith, so as to provide a singlesimultaneous saccharification and fermentation (SSF) step (not shown) soas to subject the sugar stream to saccharification in a manner asdiscussed above. The sugar stream can allow for recovery of afermentation agent from the fermentation step 226. The fermentationagent can be recovered by means known in the art and can be dried as aseparate product or, for example, can be sent to the protein separationstep 240 or other streams/steps, in the method and system 200, which canallow for capture of the fermentation agent and/or used for furtherprocessing. Fermentation agent (such as yeast or bacteria) recycling canoccur by use of a clean sugar source. Following distillation or desiredseparation step(s), the system and method 200 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step 226 may be partof an alcohol production system that receives a sugar stream that is notas desirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step 226 as the dirty sugarstream. Other options for the sugar stream, aside from fermentation, caninclude further processing or refining of the glucose to fructose orother simple or even complex sugars, processing into feed, microbe basedfermentation (as opposed to yeast based) and other various chemical,pharmaceutical or nutriceutical processing (such as propanol,isobutanol, citric acid or succinic acid) and the like. Such processingcan occur via a reactor, which can include a fermentor.

Returning now to the first holding tank 214, the dewatered solidsportion of the stream (about 70 to 25% water) next can be subjected to asecond separation step 230. And as with the first separation step 212,the second separation step 230 uses dewatering or filtration equipment,e.g., a paddle screen, a vibration screen, a filtration, scroll screenor conic screen centrifuge, a pressure screen, a preconcentrator and thelike, to accomplish further separation of the solids portion, primarilyfiber, grit, which can include protein and germ from the liquid portion,which primarily includes sugar, oil and fine solids. In one example, thedewatering equipment is a paddle screen, as above described. In oneexample, the screen size used in the second separation step 230 canrange from 25 micron to 150 micron. In another example, the screenopenings can range from 40 to 85 micron. In yet another example, thescreen openings are about 45 microns. With the second separation step230, the actual screen openings may be larger in size than those in thefirst separation step 212.

The resulting solids portion from the second separation step 230 is senton to a second holding tank 232 and the liquid portion or filtrate, maybe joined up with the ground corn flour at slurry tank 204 as part of acounter current washing setup. The resulting solids portion has a totalsolids fraction of about 35%, with the filtrate having a total solidsfraction of about 26%. The filtrate can contain particles (germ, grit,fine fiber and protein) having sizes smaller than the screen sizeopenings used in the second separation step 230.

From the second holding tank 232, the wet cake or dewatered solidsportion of the stream can be subjected to a third separation step 234.The third separation step 234 uses dewatering equipment, e.g., a paddlescreen, a vibration screen, a filtration, scroll screen or conic screencentrifuge, a pressure screen, a preconcentrator, a press and the like,to accomplish further separation of the solids portion, primarily fiber,germ, grit, which can include protein from the liquid portion, whichprimarily includes sugar, oil and fine solids. In one example, thedewatering equipment is a paddle screen, as above described. With thethird separation step 234, the actual screen openings may be larger insize than those in the second separation step 230. In one example, thescreen size used in the third separation step 234 can range from 100micron to 500 micron. In another example, the screen openings can rangefrom 150 to 300 micron. In yet another example, the screen openings areabout 200 microns. Alternatively, the actual screen openings may besmaller in size than those in the second separation step 230.

The resulting solids portion from the third separation step 234 is senton to a third holding tank 236 and the overflow liquid portion orfiltrate may be sent to a protein separation step 240, which uses, forexample, a clarifier, filtration centrifuge, decanter, stack disccentrifuge or the like, to separate the liquid portion of the streamfrom a heavier protein portion. Due to the removal of solids throughoutthe “washing” process, the total solids fraction in the solids stream atthe third holding tank 236 is about 26%. The filtrate has a total solidsfraction of about 22%. The clarifier, for example, can be provided withwashing capabilities so that wash water can be supplied thereto. Theadditional wash water allows for easier separation of the overflowliquid portion into a heavier protein portion and liquid portion. Theheavier protein portion separates from the overflow liquid portion andis removed as the underflow whereas the lighter liquid portion can beremoved as the overflow. Additionally, a two or three phase separationdevice can be utilized for this step. The overflow liquid portioncontains about 18% total solids and is sent to an overflow holding tank242. In another embodiment, prior to being sent to the proteinseparation step 240, the overflow liquid portion or filtrate from thethird separation step 234 can be subjected to an optional liquefactionstep whereat additional carbohydrates, including starches, can beconverted to sugars so that the protein portion can be furtherconcentrated up at the protein separation step 240.

The underflow protein portion next can be sent to an optional dewateringstep 244 whereat the protein portion can be subjected to filtration,including microfiltration or vacuum filtration, such as via a rotaryvacuum filter or the like. In an alternate embodiment, the proteinportion can be dewatered by being subjected to a decanter centrifuge orthe like, as are known in the art. In another embodiment, prior to beingsent to the dewatering step 244, the underflow protein portion can besubjected to an optional liquefaction step whereat additionalcarbohydrates, including starches, can be converted to sugars, allowingfor the underflow protein portion to be further concentrated up at thedewatering step 244. The filtrate from the dewatering step 244 can bereturned to overflow holding tank 242 and joined up with the overflowliquid portion from protein separation step 240. The combined filtrateat overflow holding tank 242 can be sent back to the first holding tank214 as part of the counter current washing process. In another option,the combined filtrate at overflow holding tank 242 may be joined up withthe ground corn flour at slurry tank 204, and the liquid portion orfiltrate from the second separation step 230 can be sent back to thefirst holding tank 214 as part of the counter current washing setup. Dueto the various dewatering options, the total solids fraction of thefinal dewatered protein can vary between 20 and 36%.

The dewatered protein then may be dried, such as by being sent to adryer (not shown), as is known in the art. The final dried proteinproduct can define a high protein corn meal that includes at least 40 wt% protein on a dry basis and which may be sold as pig or chicken feed,for example. In another embodiment, the high protein corn meal includesat least 45 wt % protein on a dry basis. In another embodiment, the highprotein corn meal includes at least 50 wt % protein on a dry basis. Inyet another embodiment, the high protein corn meal includes at least 60wt % protein on a dry basis. In still another embodiment, the highprotein corn meal includes at least 62 wt % protein on a dry basis andis referred to as a corn gluten meal product. In addition, the recoveredprotein can be used as a feed source to separate the zein proteins orcan be further refined to remove individual amino acids (such as lysineor other key limiting amino acid). One exemplary zein separation processfor the recovered feed source corn protein is shown and described inCheryan, U.S. Pat. No. 6,433,146, the contents of which are incorporatedherein by reference. It is noted that as the protein purity increases,the yield decreases such that the yield is variable based on the endproduct. In other examples, the recovered protein can be used as afertilizer and/or a natural herbicide or further purified to utilize forisolate proteins. To yield isolate proteins, in one example, the proteinunderflow stream may be passed through a solvent extraction process(e.g., alcohol generally or ethanol and water) (not shown) to remove allstarches, sugars and other components. Additionally the separatedproteins can be used as a food source or a flavor carrier or for healthand beauty aids.

From the third holding tank 236, the wet cake or dewatered solidsportion of the stream next can be subjected to a fourth separation step250. The fourth separation step 250 uses dewatering equipment, e.g., apaddle screen, a vibration screen, a filtration, scroll screen or conicscreen centrifuge, a pressure screen, a preconcentrator and the like, toaccomplish further separation of the solids portion, primarily fiber,germ, grit, which can include protein from the liquid portion, whichprimarily includes sugar, oil and fine solids. In one example, thedewatering equipment is a paddle screen, as above described. In oneexample, the screen size used in the fourth separation step 250 canrange from 100 micron to 500 micron. In another example, the screenopenings can range from 150 to 300 micron. In yet another example, thescreen openings are about 200 microns. With the fourth separation step250, the actual screen openings may be larger in size than those in thethird separation step 234.

The resulting solids portion from the fourth separation step 250 is senton to a fourth holding tank 252 and the liquid portion or filtrate, maybe sent to the second holding tank 232 as part of the counter currentwashing operation. The resulting solids portion has a total solidsfraction of 20%. The filtrate has a total solids content of 14%.Alternatively, the filtrate may be sent to protein separation step 240and the filtrate from the third separation step 234 may be sent to thesecond holding tank 223 in a counter current washing operation. Thefiltrate from the fourth separation step 250 contains particles havingsizes smaller than the screen size openings used in the fourthseparation step 302. Wash water can be supplied here to the fourthholding tank 252.

From the fourth holding tank 252, the wet cake or dewatered solidsportion of the stream next, which has been further diluted via theaddition of wash water, can be subjected to a fifth separation step 254whereat dewatering equipment, e.g., a paddle screen, vibration screen,filtration centrifuge, pressure screen, screen bowl decanter and thelike, is used to accomplish separation of the solid portion, whichincludes fiber from the liquid portion. The additional wash water hereallows for easier separation of the stream into primarily a fiberportion and an overflow liquid portion. One exemplary filtration devicefor the fifth separation step 254 is shown and described in Lee, U.S.Pat. No. 8,813,973, the contents of which are incorporated herein byreference. The screen openings in this step normally will be about 500microns to capture amounts of tip cap, pericarp, as well as fine fiber,but can range from about 400 micron to about 1500 micron. Residualliquid from the fifth separation step 254 may be sent to the thirdholding tank 236 as part of the counter current washing process. Thedewatered fiber contains less than 3% starch (with a range from 0.5-9%)as compared with normal dry mill fiber, which has about 4 to 6% starchin fiber. The % protein in the fiber also decreases from a conventional29% to about 12%, with a range from about 6% to about 22%, and the % oildecreases from a conventional 9% to about 2-4%, with a range from about1% to about 5%.

The resulting wet cake fiber portion from the fifth separation step 254may be further dried by a drier, as is known in the art. This wet cakefiber portion has a total solids fraction of approximately 38 to 44%.The wet cake fiber portion can be used as feed stock for secondaryalcohol or other chemical or feed or food production. The resultingcellulosic material, which includes pericarp and tip cap, and has morethan about 35% DS, less than about 10% protein, less than about 2% oil,and less than about 1% starch/sugar, can be sent to a secondary alcoholsystem, as is known in the art, as feed stock without any furthertreatment. The cellulose fiber yield is about 3 lb/bu. The fiber mayalso be burned in a biomass boiler system or used to produce a typicalDDGS type product, for example. Additionally the separated fiber streamcan be used for furfural production or for further processing into otherchemical, food, pharmaceutical and/or nutriceutical usages/applications.

While five separation steps 212, 230, 234, 250, 254 and four holdingtanks 214, 232, 236, 252 are shown and utilized here, it should beunderstood that this system and method 200 may be modified toaccommodate less than or more than that shown for recovering the sugarstream, oil, protein and/or fiber, with desirable yields and/or purity.For example, the system and method 200 can eliminate up to four of theseparation steps and up to three of the holding tanks. In anotherexample, at least three of the separation steps are utilized. In anotherexample, at least four of the separation steps are utilized. Due to thesequential separation steps 212, 230, 234, 250, 254, sugars, starch,protein and oil can be systematically washed off the fiber so that thefiber can be concentrated at the last separation step, e.g., the fifthseparation step 254, and the other components recovered and separatedout, as desired. In another example, multiple separation steps andholding tanks may be replaced by one or more filtration centrifuges,which include multiple washing stages in a single centrifuge.

Also, further modifications can be made to the above system and method200 to improve co-product recovery, such as oil recovery usingsurfactants and other emulsion-disrupting agents. In one example,emulsion-disrupting agents, such as surfactants, may be added prior tosteps in which emulsions are expected to form or after an emulsion formsin the method. For example, emulsions can form during centrifugationsuch that incorporation of surfactants prior to or during centrifugationcan improve oil separation. In one example, the syrup stream pre-oilseparation can also have emulsion breakers, surfactants, and/orflocculants added to the evaporation system to aid in enhancing the oilyield. This may result in an additional 0.05 to 0.5 lb./bu oil yieldgain.

With reference now to FIG. 5, a dry grind system and method 300 forproducing a sugar stream from grains or similar carbohydrate sourcesand/or residues, such as for biofuel production, in accordance withanother embodiment of the invention is shown. As further discussedbelow, a sugar stream, which includes a desired dextrose equivalentand/or has had removed therefrom an undesirable amount of unfermentablecomponents, can be produced after saccharification and prior tofermentation (or other sugar conversion process), with such sugar streambeing available for biofuel production, e.g., alcohol production orother processes. Here, in certain respects, system and method 300 is asimplified embodiment of the system and method 200 of FIG. 4, includingthe absence of separation and recovery of front end oil and protein, forexample.

As shown now in FIG. 5, system and method 300, like the system andmethod 200 of FIG. 4, includes a first grinding step 302 whereat grains,such as corn, for example, can be subjected to grinding so that the cornis ground into corn flour. The ground corn flour is mixed with backsetliquid at slurry tank 304 to create a slurry. Optionally, fresh watermay be added so as to limit the amount of backset needed here. Thebackset liquid includes overflow from a dewatering step 315, which is alater step in the system and method 300, and is discussed further below.

The stream from the slurry tank 304 next may be subjected to an optionalsecond grinding step 306, which involves use of a disc mill or the like,to further grind the corn. Also, prior to subjecting the stream from theslurry tank to the second grinding/particle size reduction step 306, theslurry may be subjected to an optional dewatering step, which usesdewatering equipment, e.g., a paddle screen, a vibration screen, screendecanter centrifuge or conic screen centrifuge, a pressure screen, apreconcentrator, a filter press or the like, to remove a desired amountof liquids therefrom. The further ground corn flour slurry or the streamfrom the slurry tank 304, if the second grinding step 306 is notprovided, next is subjected to liquefaction step 308, which itself caninclude multiple steps as discussed above and shown in FIGS. 3 and 4.The stream from the liquefaction step 308 is sent to an optionalsaccharification step 310 whereat complex carbohydrate andoligosaccharides are further broken down into simple sugars,particularly single glucose sugar molecules (i.e., dextrose) to producea liquefied mash. In particular, at the saccharification step 310, theslurry stream may be subjected to a two-step cook process, as alreadydiscussed in detail above.

A liquefied sugar stream having a density of about 1.05 to 1.15 grams/cccan result here. At this point, the liquefied sugar stream, whether ornot optionally subjected to the saccharification step 310, may be noless than about 90 DE. In another example, the liquefied sugar streammay be no less than 20, 30, 40, 50, 60, 70, or 80 DE. In this example,the liquefied sugar stream may not be considered desirable or “clean”enough, such as for use in biofuel or biochemical production because thetotal fermentable content of the stream may be no more than 75% of thetotal solids content in the stream. In this example, the liquefied sugarstream can have a total solids fraction of about 28-36%, such solidsincluding sugar, starch, fiber, protein, germ, oil, and ash, forexample. In yet another example, the total fermentable content of thestream is no more than 30, 40, 50, 60, or 70% of the total solidscontent in the stream. The remaining solids are fiber, protein, oil andash, for example.

After the optional saccharification step 310 (but before any potentialfermentation or sugar processing of the sugar stream), so as to providea more desirable sugar stream, the liquefied sugar stream is subjectedto a first separation step 312. If the optional saccharification step310 is not provided here, the slurry stream from the liquefaction step308 is sent to first separation step 312. The first separation step 312filters a generally liquefied solution (about 60-80% by volume), whichincludes sugar, free oil, protein, fine solids, fiber, grit and germ,and which has a total solids fraction of 28%. In particular, the firstseparation step 312 uses dewatering equipment, e.g., a paddle screen, avibration screen, screen decanter centrifuge or conic screen centrifuge,a pressure screen, a preconcentrator or the like, to accomplishsubstantial separation of the solids portion, primarily fiber, germ,grit, which can include protein from the liquid sugar stream, whichprimarily includes sugar, oil, and fine solids. As an alternativeoption, the liquefied sugar stream from the saccharification step 310can be subjected to a solids concentration process, such as anevaporation step (not shown), which can concentrate the solids viaevaporation prior to the first separation step 312.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the liquefied sugar stream may be no less than20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar stream heremay be considered desirable or “clean” enough, such as for use inbiofuel production, because the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5% of the total solidsin the stream. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 3%. In anotherexample, the total insoluble (unfermentable) solids fraction of thestream is less than or equal to 1%. In still another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 10%, 15%, 20%, 25%, or 30%. In this example, the stream sent tosugar separation step 222 may have a total solids fraction of 27%, suchsolids including sugar, starch, fiber, protein, and/or germ, forexample.

The solids portion or wet cake, which has a total solids fraction ofabout 39%, may be sent on to an optional second separation step 313, andthe sugar stream can be sent on to fermentation step 326 to convert,e.g., via a fermentor, the sugar to alcohol, such as ethanol or butanolor any other fermentation conversion process or similar sugarutilization process, followed by distillation and/or separation of thedesired component(s) (not shown), which recovers the alcohol orbyproduct(s)/compound(s) produced, as is known in the art. If notinitially provided after liquefaction step 308 earlier in the system andmethod 300, as is shown in FIG. 5, the optional saccharification step310 may be provided just prior to fermentation step 326 here or combinedtherewith so as to provide a single simultaneous saccharification andfermentation (SSF) step (not shown) so as to subject the sugar stream tosaccharification in a manner as discussed above. The sugar stream alsocan allow for recovery of a fermentation agent from the fermentationstep 326. Fermentation agent (such as yeast or bacteria) recycling canoccur by use of a clean sugar source. The fermentation agent can berecovered by means known in the art and can be dried as a separateproduct, for example or can be sent to other streams/steps in the methodand system 300, which can allow for capture of the fermentation agentand/or used for further processing. Following distillation or desiredseparation step(s), the system and method 300 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step 326 may be partof an alcohol production system that receives a sugar stream that is notas desirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step 326 as the dirty sugarstream. Other options for the sugar stream, aside from fermentation, caninclude further processing or refining of the glucose to fructose orother simple or even complex sugars, processing into feed, microbe basedfermentation (as opposed to yeast based) and other various chemical,pharmaceutical or nutriceutical processing (such as propanol,isobutanol, citric acid, or succinic acid) and the like. Such processingcan occur via a reactor, which can include a fermentor.

Returning now to the solids portion from the first separation step 312,the solids portion can be subjected to optional second separation step313 whereat dewatering equipment, e.g., a paddle screen, vibrationscreen, filtration centrifuge, pressure screen, screen bowl decanter andthe like, is used to accomplish further separation of the solid portionor wet cake, which includes fiber from the liquid portion. An optionaladdition of wash water at the second separation step 313 can allow foreasier separation of the solids portion into primarily a fiber portionand an overflow liquid portion. One exemplary filtration device for thesecond separation step 313 is shown and described in Lee, U.S. Pat. No.8,813,973, the contents of which are incorporated herein by reference.The overflow liquid portion from the second separation step 313 may besent back to the slurry tank 304, the liquefaction step 308 or thesaccharification step 310, as well as at other points within the overallsystem and method 300. Further refinements of the wet cake to separateout individual components can be utilized as previously discussed above.

In one example and with further reference to FIG. 5, the wet cake nextcan be sent to an optional dewatering step 315 whereat the wet cakeportion can be subjected to filtration or the like. In an alternateembodiment, the wet cake can be dewatered by being subjected to adecanter centrifuge or the like, as are known in the art. The filtratefrom the dewatering step 315 can be returned to the slurry tank 304 orthe saccharification step 310, as well as at other points within theoverall system and method 300. The dewatered wet cake, whether or notsubjected to optional steps 312, 315, may be dried, such as by beingsent to a dryer (not shown), as is known in the art, to produce a DDGStype product, for example.

Here, the system and method 300 has been designed such that a sugarsolution is provided along with a separate mixture of sugar/starch,germ, oil, grit, fiber and protein, which combine to produce a productsimilar to the traditional DDGS product. without any fermentation agent.The fermentation agent from a sugar stream fermentation process may beseparated and added to this combined DDGS like product. The fermentationagent may be recovered by means known in the art and may be dried as aseparate product. The fermentation agent also can be recycled or sent toother streams/steps in the method and system 300, which can allow forcapture of the fermentation agent and/or can be used for furtherprocessing. Additionally, this combined DDGS like stream has somefermentable starch/sugar contained therein, which can be fermented orfurther processed as desired.

In an alternate embodiment as shown in FIG. 6, system and method 300 a,like the system and method 300 of FIG. 5, optionally includes a sugarseparation step 322 whereat the sugar stream from the first separationstep 312 can be subjected to a clarifier, filtration centrifuge or thelike, to separate heavier components, including residual protein, fromthe sugar stream. At this point, the separated sugar stream may be noless than about 90 DE. In another example, the liquefied sugar streammay be no less than 20, 30, 40, 50, 60, 70, or 80 DE. In this example,the sugar stream here may be considered desirable or “clean” enough,such as for use in biofuel production, because the total insoluble(unfermentable) solids fraction of the stream is less than or equal to5% of the total solids of the stream. In another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 3%. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 1%. In stillanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 10%, 15%, 20%, 25%, or 30%. In thisexample, the stream sent to sugar separation step 222 may have a totalsolids fraction of 27%, such solids including sugar, starch, fiber,protein and germ, for example.

The overflow portion from the sugar separation step 322 may be sent backto join up with the solids portion or wet cake from the first or secondseparation steps 312 or 313, the second separation step 313, the slurrytank 304 or the saccharification step 310, as well as at other pointswithin the overall system and method 300 a. After the sugar separationstep 322, the sugar stream may then be further subjected to optionalseparation steps, such as those shown in FIG. 4, including optionalmicrofiltration (or similar filtration) steps, etc. The resulting sugarstream from the sugar separation step 322 (or other optional steps) canbe sent on to fermentation step 326, as above described, to convert,e.g., via a fermentor, the sugar to alcohol, such as ethanol or butanolor any other fermentation conversion process or similar sugarutilization process, followed by distillation and/or separation of thedesired component(s) (not shown), which recovers the alcohol orbyproduct(s)/compound(s) produced, as is known in the art. If notinitially provided after liquefaction step 308 earlier in the system andmethod 300 a, as is shown in FIG. 6, the optional saccharification step310 may be provided just prior to fermentation step 326 here or combinedtherewith so as to provide a single simultaneous saccharification andfermentation (SSF) step (not shown) so as to subject the sugar stream tosaccharification in a manner as discussed above. The sugar stream alsocan allow for recovery of a fermentation agent from the fermentationstep 326. Fermentation agent (such as yeast or bacteria) recycling canoccur by use of a clean sugar source. The fermentation agent can berecovered by means known in the art and can be dried as a separateproduct, for example or can be sent to other streams/steps in the methodand system 300 a, which can allow for capture of the fermentation agentand/or used for further processing. Following distillation or desiredseparation step(s), the system and method 300 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step 326 may be partof an alcohol production system that receives a sugar stream that is notas desirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step 326 as the dirty sugarstream. Other options for the sugar stream, aside from fermentation, caninclude further processing or refining of the glucose to fructose orother simple or even complex sugars, processing into feed, microbe basedfermentation (as opposed to yeast based), and other various chemical,pharmaceutical or nutriceutical processing (such as propanol,isobutanol, citric acid, or succinic acid) and the like. Such processingcan occur via a reactor, which can include a fermentor.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. For example, various enzymes (and types thereof) such asamylase, alpha-amylase, or glucoamylase, fungal, cellulase, cellobiose,protease, phytase and the like can be optionally added, for example,before, during, and/or after any number of steps in the systems andmethods 200, 300, 300 a, including the slurry tank 204, 304, the secondgrinding step 206, 306, the liquefaction step 208, 308, and/or thesaccharification step 210, 310, such as to enhance the separation ofcomponents, such as to help break the bonds between protein, starch, andfiber and/or to help convert starches to sugars and/or help to releasefree oil. In addition, temperature, pH, surfactant and/or flocculantadjustments may be adjusted, as needed or desired, at the various stepsthroughout the system and method 200, 300, 300 a, including at theslurry tank 204, 304, etc., such as to optimize the use of enzymes orchemistries. Additional advantages and modifications will readily appearto those skilled in the art. Thus, the invention in its broader aspectsis therefore not limited to the specific details, representativeapparatus and method and illustrative example shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

What is claimed is:
 1. A system for producing a sugar stream, the systemcomprising: a first grind device that is configured to receive and grindgrain and/or grain components; a slurry tank that is situated after thefirst grind device and that is configured to receive a liquid and theground grain and/or grain components, the liquid and ground grain and/orgrain components defining a slurry including starch and unfermentablecomponents; a liquefaction system that is situated after the slurry tankand that is configured to receive the slurry of the ground grain and/orgrain components, which includes the starch and unfermentablecomponents, and convert the starch in the slurry to oligosaccharides; asaccharification system that is situated after the liquefaction systemand that is configured to receive the slurry including theoligosaccharides, and convert the oligosaccharides to simple sugarsthereby producing a stream including the simple sugars and unfermentablecomponents; a first separation device selected from a paddle screen, avibration screen, a screen decanter centrifuge, a conic screencentrifuge, a pressure screen, a preconcentrator, or a filter press thatis situated after the saccharification system and that is configured toreceive and separate the stream into a solids portion including theunfermentable components and a liquid portion including the simplesugars; a sugar separation device selected from a clarifier or afiltration centrifuge that is situated after the first separation deviceand that is configured to receive the liquid portion and separate outheavier residual protein from the liquid portion, wherein the sugarseparation device is capable of producing a liquid portion, after theheavier residual protein is separated out, having a dextrose equivalentof at least 70 D.E. and a total unfermentable solids fraction that isless than or equal to 30% of the total solids content; and amicrofiltration device that is situated after the sugar separationdevice and that is configured to receive the liquid portion therefromand filter out additional insoluble components from the liquid portion,wherein the microfiltration device is capable of producing a liquidportion, after microfiltration, which defines a sugar stream having atotal unfermentable solids fraction that is less than or equal to 10% ofthe total solids content.
 2. The system of claim 1 further comprising abiofuel and/or biochemical device that is situated after themicrofiltration device and that is configured to receive the sugarstream and produce biofuel and/or biochemicals from the simple sugars.3. The system of claim 1 further including a second grind device thatfollows the first grind device and that is configured to receive andfurther grind the slurry of ground grain and/or grain components.
 4. Thesystem of claim 1 wherein the sugar stream includes the simple sugarsand free oil, and further comprising an oil separator that is situatedafter the first separation device and prior to the sugar separationdevice and that is configured to receive the liquid portion and separatethe free oil from the liquid portion to yield an oil co-product.
 5. Thesystem of claim 4 wherein the oil separator is a mud centrifuge, a twoor three phase decanter, a disc decanter, a two or three phase disccentrifuge, a flotation tank, or a dissolved air flotation tank.
 6. Thesystem of claim 4 further comprising an oil polish device that issituated after the oil separator and that is configured to receive andfurther purify the free oil from the oil separator to yield an oilco-product.
 7. The system of claim 1 further comprising a secondseparation device that is situated after the first separation device andthat is configured to receive and separate the solids portion into asecond solids portion including unfermentable components and a secondliquid portion including simple sugars.
 8. The system of claim 7 furthercomprising a third separation device that is situated after the secondseparation device and that is configured to receive and separate thesecond solids portion into a thirds solids portion includingunfermentable components and a third liquid portion including simplesugars.
 9. system of claim 8 further comprising a fourth separationdevice that is situated after the third separation device and that isconfigured to receive and separate the third solids portion into afourth solids portion, including fiber, and a fourth liquid portion. 10.The system of claim 1 wherein the unfermentable components of the solidsportion includes fiber and protein, and further comprising a secondseparation device that is situated after the first separation device andthat is configured to receive and separate the solids portion into asecond solids portion, including the fiber, and a second liquid portion,including the protein, and a protein separation device that is situatedafter the second separation device and that is configured to receive thesecond liquid portion and separate out the protein from the secondliquid portion to yield a protein co-product.
 11. The system of claim 1wherein the grain and/or grain component are one or more selected fromthe group consisting of corn, wheat, barley, sorghum, rye, rice, oats,sugar cane, tapioca, and cassava.
 12. The system of claim 1 furthercomprising a second separation device that is situated after the firstseparation device and that is configured to receive and separate thesolids portion into a second solids portion including unfermentablecomponents and a second liquid portion including simple sugars, whereinthe system is configured to combine the separated sugar stream from thefirst separation device and the separated sugar stream from the secondseparation device.
 13. A system for producing a sugar stream, the systemcomprising: a first grind device that is configured to receive and grindgrain and/or grain components; a slurry tank that is situated after thefirst grind device and that is configured to receive a liquid and theground grain and/or grain components, the liquid and ground grain and/orgrain components defining a slurry including starch and unfermentablecomponents; a liquefaction system that is situated after the slurry tankand that is configured to receive the slurry of the ground grain and/orgrain components, which includes the starch and unfermentablecomponents, and convert the starch in the slurry to oligosaccharides; asaccharification system that is situated after the liquefaction systemand that is configured to receive the slurry including theoligosaccharides, and convert the oligosaccharides to simple sugarsthereby producing a stream including the simple sugars and unfermentablecomponents; a first separation device selected from a paddle screen, avibration screen, a screen decanter centrifuge, a conic screencentrifuge, a pressure screen, a preconcentrator, or a filter press thatis situated after the saccharification system and that is configured toreceive and separate the stream into a solids portion including theunfermentable components and a liquid portion including the simplesugars; a sugar separation device selected from a clarifier or afiltration centrifuge that is situated after the first separation deviceand that is configured to receive the liquid portion and separate outheavier residual protein from the liquid portion, wherein the sugarseparation device is capable of producing a liquid portion, after theheavier residual protein is separated out, having a dextrose equivalentof at least 70 D.E. and a total unfermentable solids fraction that isless than or equal to 30% of the total solids content; a microfiltrationdevice that is situated after the sugar separation device and that isconfigured to receive the liquid portion therefrom and filter outadditional insoluble components from the liquid portion, wherein themicrofiltration device is capable of producing a liquid portion, aftermicrofiltration, which defines a sugar stream having a totalunfermentable solids fraction that is less than or equal to 10% of thetotal solids content; and a reactor that is situated after themicrofiltration device and that is configured to receive the sugarstream and produce biofuel from the simple sugars.
 14. The system ofclaim 13 wherein the reactor is a fermenter that receives the sugarstream and produces an alcohol from the simple sugars.
 15. The system ofclaim 13 further including a second grind device that follows the firstgrind device and that is configured to receive and further grind theslurry of ground grain and/or grain components.
 16. The system of claim13 wherein the sugar stream includes the simple sugars and free oil, andfurther comprising an oil separator that is situated after the firstseparation device and prior to the sugar separation device and that isconfigured to receive the liquid portion and separate the free oil fromthe liquid portion to yield an oil co-product.
 17. The system of claim16 wherein the oil separator is a mud centrifuge, a two or three phasedecanter, a disc decanter, a two or three phase disc centrifuge, aflotation tank, or a dissolved air flotation tank.
 18. The system ofclaim 16 further comprising an oil polish device that is situated afterthe oil separator and that is configured to receive and further purifythe free oil from the oil separator to yield an oil co-product.
 19. Thesystem of claim 13 further comprising a second separation device that issituated after the first separation device and that is configured toreceive and separate the solids portion into a second solids portionincluding unfermentable components and a second liquid portion includingsimple sugars.
 20. The system of claim 19 further comprising a thirdseparation device that is situated after the second separation deviceand that is configured to receive and separate the second solids portioninto a thirds solids portion including unfermentable components and athird liquid portion including simple sugars.
 21. The system of claim 20further comprising a fourth separation device that is situated after thethird separation device and that is configured to receive and separatethe third solids portion into a fourth solids portion, including fiber,and a fourth liquid portion.
 22. The system of claim 13 wherein theunfermentable components of the solids portion includes fiber andprotein, and further comprising a second separation device that issituated after the first separation device and that is configured toreceive and separate the solids portion into a second solids portion,including the fiber, and a second liquid portion, including the protein,and a protein separation device that is situated after the secondseparation device and that is configured to receive the second liquidportion and separate out the protein from the second liquid portion toyield a protein co-product.
 23. The system of claim 13 wherein the grainand/or grain component are one or more selected from the groupconsisting of corn, wheat, barley, sorghum, rye, rice, oats, sugar cane,tapioca, and cassava.
 24. The system of claim 13 further comprising asecond separation device that is situated after the first separationdevice and that is configured to receive and separate the solids portioninto a second solids portion including unfermentable components and asecond liquid portion including simple sugars, wherein the system isconfigured to combine the separated sugar stream from the firstseparation device and the separated sugar stream from the secondseparation device.